1. Field of the Invention
The present invention relates to a linear compressor, and in particular to a discharge valve system for a linear compressor which can minimize re-expansion of the compressor resulting from over-compression by smoothly discharging a compressed gas in a cylinder to a discharge chamber of a cylinder head cover, simplify an assembly process and cut production costs by decreasing a number of components.
2. Description of the Background Art
FIG. 1 is a cross-sectional view illustrating an interior of a conventional linear compressor. The constitution of the linear compressor will now be described.
A cylindrical inner casing 10 is provided in a hermetic vessel 1 in a certain shape connected to a gas suction pipe 0 through which a gas is sucked. A first lamination 15 is connected to one side of an inner circumferential surface of the inner casing 10.
A disc-shaped cover plate 20 with its center portion open is connected to one side of the inner casing 10, and a disc-shaped cover 25 is connected to the other side thereof.
One side of a cylinder 30 forming a compression chamber is connected to a through hole (not shown) at the center portion of the cover plate 20. There is provided a cylinder head cover 90 forming a discharge chamber (S) by covering one side of an empty space of the cylinder 30, and having a discharge valve system 40 and a spring 35 elastically supporting the discharge valve system 40 toward an end portion of the cylinder 30.
In addition, a piston 60 is installed in the cylinder 30 to perform a straight reciprocation, a gas flow path 60a being formed inside the piston 60. A second lamination 65 is connected to an outer circumferential surface of the cylinder 30, and is positioned separately from the first lamination 15 at a certain interval.
A magnet paddle 62 performing a straight reciprocation between the first lamination 15 and second lamination 65 is connected to the piston by a connecting body 61, thereby transferring the straight reciprocation to the piston 60.
An inside coil spring 70 is provided between an inner portion of the connecting body 61 and the second lamination 65, and an outside coil spring 75 is provided between an outer portion of the connecting body 61 and an inner portion of the cover 25, thus elastically supporting the piston 60.
A plurality of springs 80 are installed between a bottom surface of the inner casing 10 and the hermetic vessel 1, thereby elastically supporting the inner casing 10.
The operation of the conventional linear compressor will now be described.
First, when power is applied to the compressor, the magnet paddle 62 performs a straight reciprocation between the first lamination 15 and second lamination 65. As a result, the piston 60 straightly reciprocates in the cylinder 30.
A gas sucked into the hermetic vessel 1 through the gas suction pipe 0 passes through the gas flow path 60a formed at the center portion of the piston 60, and sucked and compressed in the compression chamber (C) of the cylinder 30. The compressed gas is discharged to the discharge chamber (S) by the discharge valve system 40.
A first embodiment of the discharge valve system 40 provided in the cylinder head cover 90 of the conventional linear compressor will now be described in detail with reference to FIGS. 2 to 3C.
The discharge valve system 40 includes: a disc-shaped head 41 having a discharge hole 42 at its center portion and tightly supported to the end portion of the cylinder 30; a ring-shaped valve 44 with an opening/closing flake 43 inwardly extended, the opening/closing flake 43 opening or closing the discharge hole 42 of the head; and a disc-shaped retainer 45 with its circumferential surface curvedly extended, having a plurality of discharge holes 46 in order to control an opening degree of the opening/closing flake 43, and tightly supporting the valve 44 toward the head 41.
Here, the head 41, valve 44 and retainer 45 are elastically tightly supported by the spring 35 toward the end portion of the cylinder 30.
Reference numeral 63 is a suction valve for inhaling a refrigerant gas into the piston 60. Reference numeral 64 is a cock for supporting the suction valve 63 into the piston 60. Reference numeral 95 is a discharge hole for externally discharging the gas from the discharge chamber (S).
The operation of discharging the gas compressed in the compression chamber (C) by the discharge valve system 40 will now be explained.
When the piston 60 compresses the gas in the compression chamber (C) by a forward movement, the compressed gas pushes the opening/closing flake 43 of the valve 44 through the discharge hole 42 of the head 41 at a certain point, passes through the discharge hole 46 of the retainer 45, and is sucked into the discharge chamber (S) of the cylinder head cover 90. Then, the sucked gas is discharged through the discharge hole 95 of the head cover 90.
Here, the discharge valve system 40 may be pushed by the compressed gas pressure, and thus partially discharge the gas through a gap thereof. However, only a small volume of the gas is discharged therethrough, and the gas is mostly discharged through the discharge hole 42 of the head 41, as described above.
A second embodiment of the discharge valve system 40 will now be described with reference to FIGS. 4A through 6B.
FIGS. 4A and 4B are respectively a perspective view of a head 50 and a cross-sectional view taken along line I-I' in FIG. 4A. FIG. 5 is a plan view of a valve 53. FIGS. 6A and 6B are respectively a perspective view of a retainer 55 and a cross-sectional view taken along line II-II' in FIG. 6A.
The discharge valve system 40 includes the head 50, valve 53 and retainer 55, identically to the first embodiment. As illustrated in FIGS. 4A and 4B, the head 50 is formed in a disc type having a discharge hole 51 at its center portion. A ring-shaped groove 52 is formed between the discharge hole 51 and a circumferential surface of the head 50.
As illustrated in FIG. 5, the valve 53 is formed in a spiral shape having an opening/closing unit 54 opening/closing the discharge hole 51 of the head 50 at its center portion.
As shown in FIGS. 6A and 6B, the retainer 55 is formed in a disc shape having a rounded groove 56 of a certain depth at its one side portion, a plurality of discharge holes 57 being formed in the groove 56.
The operation of discharging the gas compressed in the compression chamber (C) of the cylinder 30 by the discharge valve system 40 according to the second embodiment will now be explained.
When the piston 60 compresses the gas in the compression chamber (C) by a forward movement, the compressed gas pushes the opening/closing unit 54 of the valve 53 through the discharge hole 51 of the head 50 at a certain point, passes through the discharge hole 57 of the retainer 55, and is sucked into the discharge chamber (S) of the cylinder head cover 90. The sucked gas is discharged through the discharge hole 95 of the cylinder head cover 90.
The above-described discharge valve system for the linear compressor has a complicated structure of the head, valve and retainer. Also, the discharge hole of the head is small, and thus the compressed gas is not smoothly discharged and remains in the compression chamber of the cylinder. Therefore, the gas is over-compressed during a next operation, thereby causing re-expansion and reducing efficiency of the compressor.
In addition, an operation area of the discharge valve system to the gas compressed in the compression chamber is large, and thus the discharge valve system tends to be pushed toward the spring. When the discharge valve system is returned to the original place by the spring, it collides with the end portion of the cylinder and the inner circumferential surface of the head cover, thus causing noise and abrasion.
The discharge valve system includes a few components, and thus the assembly process is complicated and the production costs are increased.